Hezbollah fired more than 60 projectiles into Israel before noon on Sunday, a day after an Israeli strike in the heart of the Lebanese capital killed at least 20 people.

More than 65 people were wounded in the attack in Lebanon’s capital, Beirut, on Saturday. Three Israeli defense officials said the strike was an attempt to assassinate a top Hezbollah military commander, Mohammad Haidar. One of the Israeli defense officials, who requested anonymity to discuss sensitive military operations, later said that Mr. Haidar was not killed.

On Sunday, waves of air raid sirens blared throughout much of northern Israel, including the hilltop town of Safed. Israel’s military said that some of the projectiles — a term usually referring to rockets — were intercepted by air defense systems.

Magen David Adom, an Israeli emergency rescue service, said it treated a woman in northern Israel who suffered a shrapnel injury.

Hezbollah said it had fired four salvos of rockets at Israel on Sunday and one that targeted a group of Israeli soldiers in Lebanon.

The exchange of fire came as the Israeli military said it struck what it described as militant infrastructure next to a border crossing between Syria and Lebanon. It also ordered the evacuation of five villages in southern Lebanon.

Israel’s military has been intensifying operations against Hezbollah in Lebanon apparently in an attempt to pressure the militant group into a cease-fire deal. As its troops push deeper into southern Lebanon, the Israeli military has been stepping up bombardment of the Dahiya, a cluster of neighborhoods on the southern outskirts of Beirut that are effectively governed by Hezbollah.

The terms for a cease-fire between Israel and Hezbollah appear to be taking shape, according to several regional and U.S. officials briefed on the diplomacy. Despite a degree of cautious optimism, the officials warned that critical details around implementation and enforcement needed to be worked out and that disagreements could still scupper any deal.

Both Israel and Hezbollah have said they will keep fighting as the negotiations continue.